All the AL811H parts list says is 100Ω/2W, and the photo shows them to be ±10% tolerance. The AL572 parts list doesn't dig down to the component level for the parasitic suppressor assemblies. The resistors need to have very little inductance, which eliminates wirewound and some film resistors. Carbon composition could be used but they don't take heat very well, and there's plenty of that at the tube anode connectors. One expert prefers Ohmite OY (ceramic composition) resistors. You would look for pn OY101KE. Digi-Key, Mouser, Allied, and Newark all show stock on hand.

Ameritron sells the whole suppressor assembly for about $37, so I'm going to do just that.Thanks Bryan, but why doesn't one buy the "Little Devil" Ohmite type which is an original carbon resistor?Jan

Carbon composition resistors are no longer produced. As one fellow mentioned, they do drift. The 47 Ohm / 2W resistors in my SB220 took almost 40 years of almost daily use to drift to nearly 100 Ohms. However, they still functioned fine. I found New Old Stock Allen-Bradley CC resistors on eBay.

Note that, in the photo provided by W8JI, the suppressor assembly uses capacitors in series with the resistors. I found a certain ceramic composition resistor to have a lot of inductance (1.6uH), while NOS A-B carbon composition resistors had much less (20nH). The 3-1/2 turn 14ga inductors in my SB220 measured approx 80nH.

The vintage "Little Devil" Ohmite type are carbon resistors and can still be found in surplus stores. I found a whole bag full of 52 ohm/2w at a surplus store and they worked very well in my home brewed 4 tube, 572b amp.Why buy new when one can fine them surplus. It just takes some patience & time to find them.Jan N8CBX

The vintage "Little Devil" Ohmite type are carbon resistors and can still be found in surplus stores. I found a whole bag full of 52 ohm/2w at a surplus store and they worked very well in my home brewed 4 tube, 572b amp.Why buy new when one can fine them surplus. It just takes some patience & time to find them.Jan N8CBX

Carbon composition resistors are alive and well in the year 2014. They are even available in surface mount. IRC, Kamaya, KOA, Ohmite, TE Connectivity, Xicon and others manufacture CC resistors. Digikey and Mouser stock leaded CC resistors in 1/4, 1/2 and 1 watt sizes. I have not found a source of currently manufactured 2 watt CC resistors. How to keep them from shifting value too far? Don't overheat them.

Carbon composition resistors are alive and well in the year 2014. They are even available in surface mount. IRC, Kamaya, KOA, Ohmite, TE Connectivity, Xicon and others manufacture CC resistors. Digikey and Mouser stock leaded CC resistors in 1/4, 1/2 and 1 watt sizes. I have not found a source of currently manufactured 2 watt CC resistors. How to keep them from shifting value too far? Don't overheat them.

Ohmite OY Ceramic (aka Metal) Composition 2W are superior in every way (well, except in value to audiophiles) to carbon compositions.

Carbon composition resistors are alive and well in the year 2014. They are even available in surface mount. IRC, Kamaya, KOA, Ohmite, TE Connectivity, Xicon and others manufacture CC resistors. Digikey and Mouser stock leaded CC resistors in 1/4, 1/2 and 1 watt sizes. I have not found a source of currently manufactured 2 watt CC resistors. How to keep them from shifting value too far? Don't overheat them.

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